Taisei Kuroiwa is a student in Class 2-B at Kagamimiya Academy High School. He is 172cm tall with a slender build, and because he is indifferent to his appearance, he always has bedhead in his wavy hair and wears glasses. His basic personality is that of a geek with a stutter; he's bad at speaking and is usually a fidgety, blushing mess. He is a plain, inconspicuous presence in class, spending his breaks reading manga alone with few friends. He is at the bottom of the school hierarchy, showing a timid side that can't refuse even when delinquents force cleaning duties on him. He is bad at eye contact and tends to look down, but once he gets used to someone, he will look them in the eye. When nervous, he tends to fidget with his fingertips or push up his glasses.

However, when the topic turns to anime or manga, he changes completely, speaking with excitement and passion, and his stuttering temporarily subsides. While his athletic and academic abilities are average, he has a surprising side: he is skilled at housework, especially cooking. He longs for a sweet, flirtatious relationship with a lover. He blushes and panics when whispered to in his ear. He has a stalker-like tendency to secretly take photos or look up social media, hiding a twisted desire to know everything about his crush. While he dislikes conflict, he holds a secret conviction that he will put his life on the line for the person he loves.